When it comes to hydroelectric dam construction, China is unmatched. These feats of civil engineering are delivering great volumes of renewable power to an energy-hungry economy, but they’re not without controversy either.
By Jonathan Bradley and Heath Dunn
In 2023, China produced an astonishing 9.5 million GWh of electricity to satisfy the demands of an economy seeking to make a rapid shift away from dependence on imported fossil fuels.
That represents the largest rate of electricity production in the world, at more than double the second-place United States, which produced 4.5 million GWh over the same period. And while coal continues to loom large in China’s energy mix, it’s the surge in hydroelectric dam construction that dominates the country’s renewable sector.
Hydropower contributed 1.3 million GWh to China’s grid in 2023, compared to 222,000 GWh in 2000. Five of the 10 biggest hydroelectric power stations in the world, as ranked by installed capacity, are in China, and all of these came online in the past 20 years.
“They need electricity, and not only electricity; they also need water for their population,” University of Queensland Professor of Civil Engineering Hubert Chanson MIEAust CPEng told create. “It is one of the biggest nations and one of the biggest economies worldwide – if not the biggest – and it’s a country that doesn’t have a lot of natural resources.”
But China, with its mountainous topography and powerful rivers, is particularly suited to hydroelectric energy.
“The western part of China is very, very steep, reaching 5000 to 6000 m in altitude,” Chanson said. “When you generate hydroelectricity, the head difference or the altitude of your dams is one of the key parameters that enables you to generate very large electrical power.”
Satisfying this rapidly expanding demand for energy, however, is not without its logistical, environmental and technical challenges. China is a large nation, and its water resources don’t neatly align to its population distribution.
“People live on the eastern side, and the hydro resources are on the western side. Then look at the western part of China; for example, in a place like Tibet, there are massive technical challenges with sediment morphology, sedimentology, sediment transport and reservoir siltation.”
Below, create takes a closer look at five hydroelectric projects across China to consider the benefits and challenges involved in satisfying an energy-thirsty nation.
Even by China’s standards, the Three Gorges Dam is an extraordinary project.
“Three Gorges is an exception,” Chanson said. “There are one or two of its kind in the world.”
With an installed capacity of 22,5000 MW, it dwarfs other hydroelectric facilities; the next biggest, China’s Baihetan Dam, stands at 16,000 MW. Spanning 2.3 km across the Yangtze River, the resulting reservoir extends for 600 km.
It has also attracted criticism for its impact on the river’s ecosystem, the 1.2 million residents displaced during construction, and the increased risk of landslides resulting from erosion in the reservoir.
Only by comparison to the Three Gorges does Baihetan Dam look modest. The second largest hydroelectric plant in the world, and the world’s biggest arch dam, Baihetan was constructed in just four years.
With a double-curvature design developed to adapt to the deep gorge of the Jinsha River, an upper tributary of the Yangtze, the project drew on AI to help handle the logistics of cement mixing, delivery and pouring. It is also the first in the world to use one-gigawatt hydro-turbine generators, of which it has 16.
One of 11 Chinese dams on the upper reaches of the Mekong River, Xiaowan demonstrates how these structures can have geopolitical as well as environmental consequences.
The ability of China to control the flow of the river has concerned governments in Thailand, Laos, Vietnam and Cambodia, with complaints that during periods of drought, water and fish levels drop downstream while hydroelectric plants retain higher than average quantities of water.
“China is a big power, and it imposes its own needs on its neighbours,” Chanson said.
Jinping-I Dam might not have the installed capacity of some of China’s largest dams, but it towers over the others in one literal sense: this 305 m arch dam is the tallest in the world.
Located across a narrow valley with a marble and sand slate foundation, the immense height of the structure puts it at higher risk of cracking and the greater water pressure behind it induces increased demands for strength and stability.
High-strength concrete near the foundation and steel reinforcement in the upper parts of the wall help to protect from seismic activity, and a concrete cushion on the left abutment helps to compensate for the weak and weathered foundation on that bank.
Taking advantage of a 150 km bend in the Yalong River, Jinping-I is paired with Jinping-II to form a complex with a total installed capacity of 8400 MW.
Medog Hydropower Station will not be completed until next decade, but it is planned to make even the Three Gorges Dam look modest by comparison. With close to three times as much expected generating capacity, the dam will harness a 2000 m elevation drop along a 50 km stretch of Tibet’s Yarlung Tsangpo River.
Its five cascade hydro-electric dams are also highly controversial, both for its impact on local populations, cultural sites and ecosystems, but also for the control it will give China over the water supply of neighbouring nations India and Bangladesh.
“The operation of turbines is going to change the downstream flow. You operate your turbine all year round in a relatively continuous manner, and you want to hold as much water as possible. People who live downstream are going to have a regulated flow. They won’t have a low flow period, but they won’t have a high flow period, which potentially could irrigate the floodplains.”
Dams down under
According to Chanson, Australia’s topography makes it less suited to hydroelectric power generation than China, but that is no reason the country could not aspire to similarly large dam projects.
Rather, he points to pumped-storage hydroelectricity as a better route for energy generation in Australia.
“Australia has relied on and will continue to rely upon water supply and flood mitigation as our two key needs. We have big dams for flood mitigation, but most of the time our river flow will be one per cent or 0.1 per cent or 0.01 per cent of the flood discharge.”
How did engineers on the Rookwood Weir project navigate risk management in such a challenging construction environment?
It only works when I’m Nepal.
The box this comes in is 3 kilometer by 5 foot and weights 16 megaton!!!